A lithium thionyl (Li/SOCl2) battery has characteristics such as a high operation voltage of 3.5 V, a high capacity, and a low self-discharging rate of less than 1% per year, and a freezing point of a thionyl (SOCl2) electrolyte is −105° C., which allows the battery to be used within a broad range of temperature from −55° C. to 85° C. Thus, the lithium thionyl battery has been used as a primary battery power source of a device that requires characteristics of long-term use for 10 years or more, but the battery has a disadvantage of rapid battery capacity decrease under the condition of a high current.
On the contrary, although a driving voltage of the lithium sulfonyl (Li/SO2Cl2) battery is about 3.8 V, which has an advantage of maintaining a discharging capacity under the conditions of a driving voltage and a current higher than those of a lithium thionyl (Li/SOCl2) battery, rapid capacity decrease may occur at a low temperature due to a physical property, where a freezing point of a sulfonyl (SO2Cl2) electrolyte is −54° C., and thus environment for using the battery is limited by a temperature range of −20° C. to 85° C.
Also, since voltages of the lithium thionyl (Li/SOCl2) battery and the lithium sulfonyl (Li/SO2Cl2) battery are very constant during a charging process, a remaining capacity of the batteries during the use may not be checked, and thus the time for battery replacement may not be exactly recognized.
The related prior documents include Korean Patent No. 2001-0104540 (published on Nov. 26, 2001), which discloses a lithium primary battery.